Plug assembly



Nov. 30, 1948.

A. e. RICHARDSON EIAL PLUG ASSEMBLY Filed April 24. 1943 A TTOR/VPatented Nov. 30, 1948 PLUG ASSEMBLY Avery G. Richardson, Boonton, N. Jand Murray Kaplan, Brooklyn, N. Y., assignors to Federal Telephone andRadio Corporation, Newark, N. J a corporation of Delaware ApplicationApril 24, 1943, Serial No. 484,366

3 Claims. 1

Our invention relates to a plug assembly for electric cables.

When an electric cable, such as one for carrying high-frequencycurrents, is connected by means of a plug to a receptacle, it isdesirable to provide for the waterproofing of the connections betweenthe conductors of the cable at its extremity and the plug terminals. Itis also advantageous to design the plug assembly so that ready access toand inspection of such connections may be made with a minimum of tools.

The present invention has as an object, therefore, the provision ofmeans for accomplishing the above results in an improved manner.

Another object of the invention is to provide a plug assembly designedso as to obviate the tendency of conventional plugs to break connectionsdue to a twist of the cable.

A further object of the invention is to provide a method of attachingthe retaining nut to the plug body in a non-separable manner.

The invention still further includes an improved method of grounding thecable to the plug body.

Other objects and advantages of the invention will be apparent from thefollowing description of one embodiment of the invention and from thedrawings, in which:

Fig. 1 is a view, partly in section, of a preferred embodiment of thepresent invention;

Fig. 2 is an end view of Fig. 1;

Fig. 3 is a plan view of one of the parts of Fig. 1;

Fig. 4 is a side sectional View of Fig. 3;

Fig. 5 is a side view of another of the parts of Fig. 1;

Fig. 6 is a side view, partly in section, of two other parts of Fig. 1.

In Fig. l is shown a partly sectional view of a plug assembly for anelectrical cable in accordance with the present invention. A cable A isprovided with a pair of spaced conductors I and 8 respectivelysurrounded by individual insulating coverings 9 and ID, which in turn,may be surrounded by separate metal sheaths 9A and IDA (-Fig. 2). Overthese separate sheaths 9A and IDA is a common outer sheath I I which maybe formed of copper braid, while an outer insulating covering I2encloses the sheath II. The entire cable construction is thus of a moreor less conventional type, and it is to be understood that the inventionis not limited to this or any other particular type of cable.

A tubular body I9 is also shown in Fig. 1 enclosing an extremity of thecable A. A disc I of a suitable insulating material with three prong 22,23 and 24 in spaced apart relation therein is positioned removably inthe body I9. A second insulating disc 20 has three openings therein toreceive prongs 22, 23 and 24, and slides over such prongs to set face toface with disc H as shown.

The prongs 22, 23 and 24 are respectively provided with terminals I3, I4and I5 on the inner face of disc 2I. Terminal I3 is joined by means suchas soldering to conductor I of cable A. Terminal I5 is joined toconductor 8. Terminal I4 is joined, preferably by soldering, to theouter sheath I I of cable A by a connecting wire I8.

Partly enclosing the exposed conductors I and B and the connecting wireI8, and adjacent the disc 2I, is an insert retainer sleeve 25 having acut-out portion 26 in the outer surface thereof to allow for inspectionof or access to the connections between the cable conductors and theprong terminals. This cut-out portion may best be seen by referring toFigs. 3 and 4 which show detailed views of the insert retainer sleeve25.

A central opening 28 (Fig. 4) in retainer sleeve 25 allows for insertiontherein of cable A, this opening having a shape corresponding to thecross-sectional shape of cable A. A sloping shoulder 21 is formed onretainer sleeve 25 as shown in Fig. 4.

A ring-shaped sleeve 29 of rubber or other resilient material encirclesthe cable A and adjoin-s a portion of insert retainer sleeve 25. Asloping section 33 of the outer surface of sleeve 29 is designed forparallel relationship with shoulder 21 of insert retainer sleeve 25 asshown in Fig. 1.

Between the shoulder 21 of insert retainer sleeve 25 and the slopingsection 33 of resilient sleeve 29 is positioned a grounding ferrule alsoshown in Fig. 5. This ferrule comprises a ring-shaped disc 32 ofconducting material such as copper and has an inwardly-extendingtongue-shaped portion 30 bent at right angles to the plane of disc 32,the tongue 30 thus being substantially parallel to the axis of cable A.The tongue 30 is also designed to lie flat on the surface of cable A,and an opening 3] in tongue 30 permits soldering or other connection oftongue 30 to sheath I I as shown in Fig.

3 1. Since one face of ring-shaped disc 32 constituting the groundingferrule lies flat against the shoulder 21 of insert retainer sleeve 25,it will be seen that an electrical connection is established betweensheath ll of cable A and the insert retainer sleeve 25. Since suchsleeve 25 as Well as body [9 is formed of conductive material, itfollows that the cable shielding is efiectively grounded to the body ofthe plug assembly.

A compression sleeve 34 is inserted part way into body l9 so as tocontact resilient sleeve 29 as shown in Fig. l. An end view of thiscompression sleeve may be seen in Fig. 2. Two threaded openings 3i and38 are formed in an extending portion of body I9, and two openings 39and 49 are formed in oppositely-disposed portions of compression sleeve34. Bolts 35 and 36 are designed for insertion in these openings asshown in Fig. 1.

In assembling the plug, the cover t2 of cable A is cut back to exposethe common braided sheath ll. The common sheath H (and the individualconductor sheaths 9A and IDA) are then out back to expose the individualinsulating coverings 9 and II], which are in turn partly removed so asto expose the conductors l and 8. Compression sleeve 34 containing bolts35 and 36 is slipped over the end of the cable, as is also resilientmember 29, grounding ferrule 32, and insert retainer sleeve 25, theseparts being properly positioned relative to each other. The insulatingdisc 2l (with the terminals I3, I4 and 15, as well as the prongs 22, 23and 24 already securely positioned therein) is then brought up. Thecable conductor 1 is soldered to terminal I3, conductor 8 is soldered toterminal [5, and connecting wire i8 is soldered to both terminal I4 andsheath 1 I.

When these connections are completed, insert retainer sleeve 25 is drawnback to partly enclose the connections, followed by the groundingferrule 32, the resilient member 29, and the compression sleeve 34. Theopening 3| in tongue 30 of grounding ferrule 32 now permits the tongue39 to be soldered through opening 26 to the sheath Insulating disc 20 isnow slipped over the .prongs 22, 23 and 24. and the above assemblyinserted in body IS. A shoulder 48 on the inner wall of body l9 contactsshoulder 49 on insert in a compression of resilient member 29 betweeninsert retainer sleeve 25 and compression sleeve (The presence ofgrounding ferrule 32 does not interfere with this operation.) Thispressure on resilient member 29 results in a tight union between suchmember and all points of its enclosure,'rendering the cable end of theplug assembly substantially waterproof. An opening 53 between theresilient member 29 and the inner wall of body i9 allows for distortionof the resilient member due to action of compression sleeve 34.

As hereinbefore explained, the opening or window 25 in retainer sleeve25 permits ready inspection of or access to the soldered connections.

'Grounding ferrule 32 grounds sheath ll of cable A to body l9 throughretainer sleeve 25.

Compression sleeve 34 is provided with an extending portion 4| whichextends away from the body l9 of the plug assembly. This extendingportion 4! is designed to loosely encircle the cable covering [2, andany twisting or bending of cable A at a point removed from the plugassembly will be transmitted to and resisted by such extending portion4| rather than the body l9. This design tends to substantially reducethe possibility of breakage or damage to the soldered connectionsbetween the conductors of cable A and the plug terminals.

The method of inserting the plug assembly into a receptacle ofconventional type will not be discussed here. However, the inventiondoes provide for a novel method of associating the engaging nut 42 withthe body l9 in a non-separable manner.

As best shown in Fig. 6, engaging nut 42 has an annular slot 44 on theinner surface thereof. An opening 45 is formed in one side of this slot44. A retaining ring 46 is split as shown in Fig. 6 and designed to beinsertable through opening 45 into slot 44, by the method of placing oneend of the ring into the opening and then feeding the ring into theopening until the other end of the ring snaps into place in the slot toremain permanently therein.

The outer surface of bod 59 has a circular ridge 43 shown in Fig. 1. Theengaging nut 42 is placed over the end of the body until ridge 43contacts a shoulder 47 (Fig. 6) on the inner surface of engaging nut 42.(In use, a gasket is placed between ridge 43 and shoulder so as torender this end of the plug assembly waterproof). When the retainingring 46 is in place in slot 44 it rotatably positions nut 42 on bodyl9,but prevents a subsequent removal of the nut.

While We have described above the principles of our invention inconnection with specific apparatus, and particular modificationsthereof, it is to be clearly understood that this description is madeonly by way of example and not as a limitation on the scope of ourinvention asset forth in the objects of our invention and theaccompanying claims.

We claim:

1. In a plug assembly for the extremity of an electric cable having oneor more conductors, the combination of a tubular body to receive the endof said cable, a disc-shaped insert of insulating material disposed insaid tubular body, a plurality of prongs positioned on one face of saiddisc-shaped insert, each of said prongs having a terminal on theopposite face of said insert, means forming electrical connectionswithin said body between said. terminals, respectively, and theconductors of said cable, an insert retainer sieeve within. said body,adjacent said disc-shaped insert, a ring-shaped resilient 'member withinsaid body, adjacent said retainer sleeve, and around said cable, acompression sleeve partially within said body, adjacent said resilientmemher, and around said cable, and tightening means on the exterior ofsaid body and said compression sleeve, whereby operation of saidtightening means will tend to compress said'resilient member betweensaid compression sleeve and said retainer sleeve.

2. The plug assembly defined in claim 1, whercin said cable is equippedwith. a grounding sheath enclosing said conductors, in combination witha groundin ferrule disposed between said insert retainer sleeve and saidring-shaped resilient member, said ferrule being electrically joinedwithin said retainer sleeve to said sheath so as to ground said sheathto said retainer sleeve.

3. The plug assembly defined in claim 1, wherein said insert retainersleeve has a cut-out portion permitting access to and inspection of saidelectrical connections Without alterin the position 01 said retainersleeve With respect to said cable.

AVERY G. RICHARDSON. MURRAY KAPLAN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 798,078 Simpson 1- Aug. 29, 1905944,877 Koschinski Dec. 28, 1909 1,345,473 Benjamin July 6, 19201,673,644 Shoe June 12, 1928 Number Name Date Edmonds June 10, 1930Proos Nov. 4, 1930 Borden May 31, 1932 Bondeson Sept. 25, 1934 TornblomAug. 22, 1939 Roper Nov. 28, 1939 Finlayson Jan. 6, 1942 Hayes Dec. 8,1942 Markey Dec. 29, 1942 Markey Oct. 12, 1943 FOREIGN PATENTS CountryDate Austria Feb. 25, 1936 Great Britain June 30, 1937 Great BritainJuly 15, 1941

